1). Field of the Invention
This invention relates to a method and apparatus for transporting semiconductor substrates, in particular, to a method and apparatus for transporting semiconductor substrates between processing modules within a semiconductor substrate processing system.
2). Discussion of Related Art
Integrated circuits are formed on semiconductor substrates, such as wafers. The wafers are then sawed (or “singulated” or “diced”) into microelectronic dice, also known as semiconductor chips, with each chip carrying a respective integrated circuit, or device. Each semiconductor chip is then mounted to a package, or carrier, substrate. The packages are often mounted to a circuit board, which may be installed in a computer.
Numerous steps may be involved in the creation of the integrated circuits, such as the formation and etching of various semiconducting, insulating, and conducting layers, as well as cleaning the substrates between the formation of these various layers. The systems used for processing the semiconductor substrates often include several different types processing modules. In order for the substrates to be processed by each different type of module, the substrates must be transported between the modules.
Typically, the substrates are transported between the modules by robots that include substrate, or wafer, grippers, or “active end effectors” to “grab” the substrate from one module and place the substrate in the next module. The wafer grippers often have moving parts which in order to securely grip the substrates must contact, or touch, the upper, or “device,” surface of the substrate and/or the lower, or “non-device,” surface of the substrate.
This contact with the upper and lower surfaces of the substrates often leads to the devices being contaminated and damaged during transportation between the various processing modules. Additionally, the moving parts of the grippers add to the costs of the systems, thus increasing the costs of manufacturing the integrated circuits. Furthermore, repeated exposure to semiconductor processing liquids, such as deionized water and other chemicals, can damage the moving parts, which increases the maintenance costs of the systems.